1. Field of the Invention
This invention relates to novel 3-aminoindazole derivatives which are useful in therapeutics. More specifically, this invention relates to novel 3-aminoindazole derivatives which have valuable effects for anti-inflammation, analgesic activity and for suppressing digestive tract ulcers, a side effect caused by using acidic non-steroidal anti-inflammatory drugs. Further, this invention relates to a process for preparing the 3-aminoindazole derivatives.
2. Description of the Prior Art
Various experiments to obtain novel and useful anti-inflammatory drugs by many researchers in the field of synthetic organic chemistry have been done. Most of the experiments relate to the synthesis or testing of steroidal hormone compounds such as corticosteroids, and acidic non-steroidal substances such as phenylbutazon and indomethacin. On the other hand, the effects of basic non-steroidal agents have not been reported in development of novel, superior and improved anti-inflammatory agents, even though the basic non-steroidal agents have the same effects as the usual acidic non-steroidal compounds, and further, the basic agents advantageously show almost no side effects such as digestive tract ulcers, caused by the acidic non-steroidal compounds.
3-Aminoindazole was first reported in Bamberger, Liebigs Ann., 305, 339 (1899).
A 3-aminoindazole derivative whose phenyl ring has a halogen group or a trifluoromethyl group and whose 3-position is an amino group or an amino group substituted with a lower alkyl group is described in U.S. Pat. No. 3,133,081. This patent discloses usage of these commpounds as drugs having central nervous system activity, and as muscle relaxants, analgesics, antipyretics and tranquilizers. However, pharmacological data of the derivatives are not disclosed. Moreover, the compounds of U.S. Pat. No. 3,133,081 have never been actually used as medicines.
Silvest et. al., Arzneim-Forsch, 16, 59 (1966) report that 1-benzyl-3-(3-dimethylaminopropoxy)indazole hydrochloric acid is effective against primary inflammation. For example, benzydamine hydrochloride is actually used as a medicine.
U.S. Pat. No. 3,681,382 discloses other 3-aminoindazole derivatives wherein hydrogen atom linked with the 1-position nitrogen atom is substituted by an aryl group and whose 3-position is substituted by a .omega.-aminoalkyl group or an .omega.-heterocyclic aminoalkyl group having 1 to 5 carbon atoms together with the nitrogen atom; or substituted by a .omega.-aminoalkylamido group or an .omega.-heterocyclic aminoalkylamido group having 1 to 5 carbon atoms together with the nitrogen atom. The patent also discloses usage of these compounds as antidepressants and anti-inflammatory drugs. However, pharmacological data are not disclosed in the U.S. Patent. Moreover, these compounds have never been actually used as medicines.
Though some indazole derivatives are known, as described above, the prior art fails to teach or suggest the 3-aminoindazole derivatives of this invention.